Update docs to refer to version.html (#1631)

Author: jainapurva

docs/source/_templates/layout.html

@@ -2,7 +2,7 @@
 
 {% block sidebartitle %}
     <div class="version">
-        <a href='index.html'>{{ version }} &#x25BC</a>
+        <a href='https://pytorch.org/ao/versions.html'>{{ version }} &#x25BC</a>
     </div>
     {% include "searchbox.html" %}
 {% endblock %}